Non-uniform Aggregation Research Articles

Self‐Regulating Interfacial Space Charge through Polyanion Repulsion Effect towards Dendrite‐Free Polymer Lithium‐Metal Batteries

AbstractUncontrolled transport of anions leads to many issues, including concentration polarization, excessive interface side reactions, and space charge‐induced lithium dendrites at the anode/electrolyte interface, which severely deteriorates the cycling stability of lithium metal batteries. Herein, an asymmetrical polymer electrolyte modified by a boron‐containing single‐ion conductor (LiPVAOB), is designed to inhibit the nonuniform aggregation of free anions in the vicinity of the lithium anode through the repulsion effect improving the lithium‐ion transference number to 0.63. This LiPVAOB exerts a repulsion interaction with free anions even at a long distance and a selective effect for free anions transport, which diminishes uneven aggregation of free anions at the interface and suppresses space charges‐induced lithium dendrites growth. Consequently, the assembled Li||Li cell delivers an ultra‐long cycle for over 5400 h. The Li||LiFePO4 cell exhibits outstanding cycle performance with a capacity retention of 93% over 4500 cycles. In particular, the assembled high‐voltage Li||Li1.2Ni0.2Mn0.6O2 cell (charged to 4.8 V) exhibits good cycle stability with a high specific capacity of 245 mAh g−1. This designed polymer electrolyte provides a promising strategy for regulating ion transport to inhibit space charge‐induced lithium dendrite growth for high‐performance lithium metal batteries.

Wear characteristics, reduction techniques and its application in automotive parts – A review

Wear phenomenon impact the operating efficiency and service life of engineering materials due to the influence of surface interaction at different working conditions. Successive tribological studies on wear-resistant materials in the last decade is estimated at approximately 40% of friction and wear, including laboratory tests. Most locally improvised wear testers in accordance with American Society for Testing and Materials (ASTM) and European (EN) standards, though, achieve 95–97% parametric accuracies with reduced cost, they hardly harmonize degradation and Archards coefficients for all possible wear factors, providing little data for simulation of mechanical and chemical wears which are responsible for non-uniform aggregation of wear patterns in practice. Complexities of intermeshing factors which combine to influence the effectiveness of developed test devices span over loads, speeds, temperatures, pressures, and ambience for various applications. This study highlights the techniques of wear characterization, test standards, and wear reduction with emphasis on surface texturing for improved eta/beta phase re-arrangements at low working temperatures in the enhancement of grain contraction during high bias-voltage cathodic substrate multi-phase coating, phosphating during pretreatments using peening techniques, residual stress reduction during cryogenic heat treatments as well as the impact of suitable architectural matrix composite strengthening, microstructures, and material reinforcements as suitable factors to influence improved tribological behaviors in materials. Optimal additive manufacturing (AM‐fabricating) techniques with pretreatments, thermal cycling, and tempering can engineer enhanced anti-tribocorrosion in automotive components.

Choosing an Optimal Solvent Is Crucial for Obtaining Cell-Penetrating Peptide Nanoparticles with Desired Properties and High Activity in Nucleic Acid Delivery.

Cell-penetrating peptides (CPPs) are highly promising transfection agents that can deliver various compounds into living cells, including nucleic acids (NAs). Positively charged CPPs can form non-covalent complexes with negatively charged NAs, enabling simple and time-efficient nanoparticle preparation. However, as CPPs have substantially different chemical and physical properties, their complexation with the cargo and characteristics of the resulting nanoparticles largely depends on the properties of the surrounding environment, i.e., solution. Here, we show that the solvent used for the initial dissolving of a CPP determines the properties of the resulting CPP particles formed in an aqueous solution, including the activity and toxicity of the CPP-NA complexes. Using different biophysical methods such as dynamic light scattering (DLS), atomic force microscopy (AFM), transmission and scanning electron microscopy (TEM and SEM), we show that PepFect14 (PF14), a cationic amphipathic CPP, forms spherical particles of uniform size when dissolved in organic solvents, such as ethanol and DMSO. Water-dissolved PF14, however, tends to form micelles and non-uniform aggregates. When dissolved in organic solvents, PF14 retains its α-helical conformation and biological activity in cell culture conditions without any increase in cytotoxicity. Altogether, our results indicate that by using a solvent that matches the chemical nature of the CPP, the properties of the peptide-cargo particles can be tuned in the desired way. This can be of critical importance for in vivo applications, where CPP particles that are too large, non-uniform, or prone to aggregation may induce severe consequences.

Specific Interactions in the Model of Mixed Multicomponent Micelles: Predicting Aggregation Behavior and Details of Structure

Modeling of multicomponent micellar aggregates is important for screening and selecting formulations in a variety of engineering applications, including micelle-mediated separation, drug delivery and nanoreactors. Typically, the constituent molecules of such aggregates have complex chemical structure and are engaged in specific and nonspecific interactions with one another and with the hydration water. Description of these interactions in the strongly nonuniform aggregates is very difficult, impeding the development of the theoretical models. In this work we extend to the multicomponent aggregates a molecular-thermodynamic model that describes the hydrogen bonding and other specific interactions in the hydrated corona. The model is formulated for an arbitrary number of nonionic and ionic amphiphiles that self-assemble into polydisperse aggregates in an aqueous solution. For describing the aggregation equilibrium together with the material balance in this solution, a simple method is suggested and tested. We illustrate application of our model by predicting aggregation equilibrium and characteristics of the three-component aggregates in the aqueous mixture of the nonionic surfactant Triton X-114, a micelle-forming alkylimidazolium ionic liquid (1-methyl-3-octylimidazolium chloride), and n-octanol. Our calculations suggest that the tails of the octanol molecules are deeply buried in the cores of the mixed micelles with only one methylene group penetrating the coronae and that the entire hydrocarbon tail of the ionic liquid resides in the core. Taking into account the populations of polydisperse spherical and rodlike aggregates, we model equilibrium partitioning of the components between the aggregates and the surrounding aqueous solution. The model predicts that addition of the ionic liquid to the mixture promotes the partitioning of n-octanol into the Triton-rich micelles.

Production of homogenous size‐controlled human induced pluripotent stem cell aggregates using ring‐shaped culture vessel

Aggregate size is an important parameter that determines the cell fate and quality of the resulting human-induced pluripotent stem cells (hiPSCs). Nowadays, large-scale suspension culture is a common method for scaling-up the biomanufacturing of hiPSCs to realize their practical application. However, this culture system exhibits a complex hydrodynamic condition resulting from the different mixing conditions of culture media, which potentially produce non-uniform aggregates, which may decrease the quality of the cell yield. Here, we performed expansion in a ring-shaped culture vessel and compared it with three other suspension-based culture systems to evaluate the uniformity and characteristics of hiPSC aggregates. Morphologically, the hiPSC aggregates formed and expanded in the ring-shaped culture vessel, resulting in small and uniform aggregates compared to the other culture systems. This aggregate population showed a decent mass transfer required for the exchange of biochemical substances, such as nutrients, growth factors, oxygen, and waste metabolic products, inside the aggregates. Thus, better metabolic performance and pluripotency markers were achieved in this system. Interestingly, all culture systems used in this study showed different tendencies in embryoid body differentiation. The smaller aggregates produced by sphere ring and dish bag tended to differentiate toward ectodermal and mesodermal lineages, while predominantly larger aggregates from the 6-well plates and spinner flask exhibited more potential for endodermal lineage. Our study demonstrates the production of a decent homogenous aggregate population by providing equal hydrodynamic force through the ring-shaped culture vessel design, which may be further upscaled to produce a large number of hiPSCs for clinical applications.

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses.

In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene. The chips fabricated allowed us to detect the influenza viruses in a concentration range of 10−16 g/mL to 10−10 g/mL in PBS (phosphate buffered saline). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that these defects are responsible for the inhomogeneous aggregation of antibodies and influenza viruses over the functionalized graphene surface. Non-uniform aggregation is responsible for a weak non-linear logarithmic dependence of the biosensor response versus the virus concentration in PBS. This feature of graphene nano-arrangement affects the reliability of detection of extremely low virus concentrations at the early stages of disease.

3D reconstruction of dynamic behaviors of vacuum arcs under transverse magnetic fields via computer tomography.

The transverse magnetic field (TMF) contacts make the vacuum arcs deviate from the axisymmetric structure, so complete spatiotemporal evolution information of the plasma cannot be obtained by adopting one- or two-dimensional (2D) diagnostic methods. To address the issues, computer tomography was introduced in this paper. First, a multi-angle diagnostic imaging system based on split fiber bundles was proposed, which used a high-speed camera to simultaneously acquire eight angles of the arc image over time. In addition, a tomography algorithm called the maximum likelihood expectation maximum with Split Bregman denoising was proposed to reconstruct the dynamic spatiotemporal characteristics of the arc under complex conditions. Then, the three-dimensional (3D) distribution of Cu i and Cr i particles inside the contact gap was obtained by adopting optical filters. The 3D distribution of the vacuum arc had shown an obvious asymmetrical pattern under the TMF contacts, and there was a ring-like aggregation zone inside the arc, which can cause severe ablation on the anode contacts. According to the reconstructed 3D distribution of Cu i and Cr i, it is found that the metal vapor was mainly concentrated near the electrode surface and showed a clear distribution of non-uniform aggregates, while the concentration of particles in the gap was low. Moreover, on the cathode surface, the cathode spots moved in the form of groups driven by the TMF, while the anode surface was ablated by the electric arc, and the metal vapor existed in the form of bands.

Thickness Dependence of Resistance Components of a LiNixCoyMn1-x-yO2-Based Positive Electrode for Lithium Ion Batteries

Dependence of charge-transfer resistance (R ct ) on thickness of positive electrodes for high-power lithium-ion batteries (LIBs) was investigated. The results of the investigation show that R ct of a LiNixCoyMn1-x-yO2 (NCM)-based positive electrode is increased by decreasing electrode thickness to less than 15 μm, while R ct of electrodes with thickness greater than 15 μm stayed almost constant. Scanning spreading resistance microscopy indicated that the electronic resistances of thinner electrodes were higher than those of thicker electrodes. Given that result, we consider that the formation of an electrically conductive network in the thinner electrode is insufficient compared to that formed in the thicker electrode. Focused-ion-beam scanning-electron-microscopy observation of an electrode with a higher R ct revealed that acetylene black (AB) as an electron conductor and poly-vinylidene-difluoride binder were agglomerated non-uniformly, and large pores formed among the non-uniform aggregates. Presumably, the non-uniform distribution of aggregates and formation of large pores resulted in an insufficient electrically conductive network between the aggregates, which resulted in increased R ct .

Microstructure evolution and coercivity enhancement in Pr50Dy20Cu15Ga15-doped hot-deformed Nd-Fe-B magnets

To improve the coercivity (Hcj) and thermal stability of hot-deformed (HD) Nd-Fe-B magnets, Pr50Dy20Cu15Ga15 (at.%) alloy powders with minor heavy rare earth (HRE) are introduced. The magnetic properties, thermal stability and microstructure of the HD magnets with different amounts of Pr50Dy20Cu15Ga15 alloy powders are investigated. The Hcj of the HD magnets is enhanced from 1242 kA/m to 1595 kA/m by doping 3 wt.% Pr50Dy20Cu15Ga15 alloy powders. The thermal stability of the doped HD magnet is also improved at high temperatures. The better isolation of Nd2Fe14B grains by rare earth-rich (RE-rich) phases and the formation of local high-anisotropy (Nd, Pr, Dy)2Fe14B hard magnetic phases are the main reasons for the increase of Hcj. Notably, the non-uniform aggregation of RE-rich phases results in the inhomogeneity of magnetic anisotropy, which eventually leads to the large openness of the recoil loops. This study gives an intuitive view on the relationship between microstructure evolution and magnetic properties of the HD magnets.

Typical and Atypical Morphology of Non-volatile Particles from a Diesel and Natural Gas Marine Engine

Non-volatile particle emissions from a marine engine fueled by either diesel or natural gas (NG) blended with diesel pilot gas were investigated via transmission electron microscopy (TEM). The most common particles (> 95% by number) were soot aggregates. These “typical” aggregates exhibited primary particle diameters of 20.7 ± 1.9 and 26.9 ± 1.7 for 100 nm aggregates when diesel and NG fuel were used, respectively. Highly non-uniform aggregates, with distinct groups of smaller and larger monomers, were visible in all of the samples but occurred most frequently with diesel fueling at high loads. The observed “atypical” particles included super-aggregates, small compact aggregates, spheres, mineral-like polyhedral particles, and fibers. Such particles, although rare (averaging 3% by number, as calculated by counting the number of particles for each type depicted in all of the collected images), were found in most of the samples and could have been produced by a variety of mechanisms. For instance, the spheres (approximately 300 nm in diameter) most likely arose from metals within the lubricating oil.

Enhanced foaming and emulsifying properties of high-pressure-jet-processed skim milk

The effect of high pressure jet (HPJ) processing on foaming and emulsifying properties of skim milk was studied. Viscosity of milk significantly increased at HPJ processing pressures ≥300 MPa and particle size distribution became bimodal for milk processed at 400 or 500 MPa. Cryo-electron microscopy of milk processed at 400 or 500 MPa showed formation of non-uniform aggregates of proteins, which were distinctly larger than intact casein micelles. HPJ processing markedly increased the foam expansion index of milk. In addition, significant increases in foam volume stability index and emulsion activity index were observed for milk following HPJ processing at ≥300 MPa. It is suggested that the structural modifications occurring in the micelles due to HPJ processing are primarily responsible for the observed changes in interfacial properties. The ability to modify key functional properties of milk by HPJ processing opens opportunities for milk-based novel ingredient manufacturing.

Effects of TiC content on microstructure, mechanical properties, and thermal conductivity of W-TiC alloys fabricated by a wet-chemical method

W-(0–0.9)TiC (wt.%) alloys were prepared by a wet-chemical method and spark plasma sintering. The effects of TiC content on the microstructures, mechanical properties, and thermal conducting properties of the prepared W-TiC alloys were investigated. The results revealed that the average grain size of the W-(0–0.9)TiC alloys decreased, and their average TiC particle size increased with the increase of TiC content. The bending fracture strengths of the prepared samples increased significantly with increased TiC content in the range of 0–0.5%, which was attributed to the uniform distribution of TiC particles with a high proportion located in the tungsten grain interiors. The W-0.5TiC alloy exhibited the best mechanical properties with the highest relative density, bending strength, and flexural strain of 97.61%, 1065.72MPa, and 1.23%, respectively. Moreover, the thermal conductivities of the W-(0.1–0.5)TiC alloys were slightly lower than those of pure tungsten at all testing temperatures. However, the mechanical properties and thermal conducting properties of the W-0.7TiC and W-0.9TiC alloys were significantly deteriorated due to the non-uniform aggregation of TiC particles at the tungsten grain boundaries.

Self-assembly and electrical characteristics of 4-pentynoic acid functionalized Fe3O4-γ-Fe2O3 nanoparticles on SiO2/n-Si

A novel investigation on a relationship between temperature-influential self-assembly (70–300°C) of 4-pentynoic acid functionalized Fe3O4-γ-Fe2O3 nanoparticles (NPs) on SiO2/n-Si with electrical properties was reported with the interests for metal-oxide-semiconductor applications. X-ray diffractometer (XRD) analysis conveyed that 8±1nm of the NPs were assembled. Increasing heating temperature induced growth of native oxide (SiO2). Raman analysis confirmed the coexistence of Fe3O4-γ-Fe2O3. Attenuated Total Reflectance Infrared (ATR-IR) spectra showed that self-assembly occurred via SiOC linkages. While SiOC linkages were broken down at elevated temperatures, formations of Si-OH defects were amplified; a consequence of physisorbed surfactants disintegration. Atomic force microscopy (AFM) showed that sample with more physisorbed surfactants exhibited the highest root-mean-square (RMS) roughness (18.12±7.13nm) whereas sample with lesser physisorbed surfactants displayed otherwise (12.99±4.39nm RMS roughness). Field Emission Scanning Electron Microscope (FE-SEM) analysis showed non-uniform aggregation of the NPs, deposited as film (12.6μm thickness). The increased saturation magnetization (71.527Am2/kg) and coercivity (929.942A/m) acquired by vibrating sample magnetometer (VSM) of the sample heated at 300°C verified the surfactants’ disintegration. Leakage current density-electric field (J-E) characteristics showed that sample heated at 150°C with the most aggregated NPs as well as the most developed SiOC linkages demonstrated the highest breakdown field and barrier height at 2.58×10−3 MV/cm and 0.38eV respectively. Whereas sample heated at 300°C with the least SiOC linkages as well as lesser aggregated NPs showed the lowest breakdown field and barrier height at 1.08×10−3 MV/cm and 0.19eV respectively. This study opens up better understandings on how formation and breaking down of covalent linkages as well as accumulation of defects, particularly prior temperature influential self-assembly at the interfaces, affected electrical breakdown field and barrier height. Hence, possible future development of self-assembly silicon-based metal-oxide-semiconductor (MOS) structure particularly in the presence of SiO2 can be deliberated.

Correcting the Relative Bias of Light Obscuration and Flow Imaging Particle Counters

Industry and regulatory bodies desire more accurate methods for counting and characterizing particles. Measurements of proteinaceous-particle concentrations by light obscuration and flow imaging can differ by factors of ten or more. We propose methods to correct the diameters reported by light obscuration and flow imaging instruments. For light obscuration, diameters were rescaled based on characterization of the refractive index of typical particles and a light scattering model for the extinction efficiency factor. The light obscuration models are applicable for either homogeneous materials (e.g., silicone oil) or for chemically homogeneous, but spatially non-uniform aggregates (e.g., protein aggregates). For flow imaging, the method relied on calibration of the instrument with silica beads suspended in water-glycerol mixtures. These methods were applied to a silicone-oil droplet suspension and four particle suspensions containing particles produced from heat stressed and agitated human serum albumin, agitated polyclonal immunoglobulin, and abraded ethylene tetrafluoroethylene polymer. All suspensions were measured by two flow imaging and one light obscuration apparatus. Prior to correction, results from the three instruments disagreed by a factor ranging from 3.1 to 48 in particle concentration over the size range from 2 to 20μm. Bias corrections reduced the disagreement from an average factor of 14 down to an average factor of 1.5. The methods presented show promise in reducing the relative bias between light obscuration and flow imaging.

Excitation energy migration in yellow fluorescent protein (citrine) layers adsorbed on modified gold surfaces

The nature of functional proteins adsorbed on solid surfaces is interesting from the perspective of developing of bioelectronics and biomaterials. Here we present evidence that citrine (one of yellow fluorescent protein variants) adsorbed on modified gold surfaces would not undergo denaturation and energy transfer among the adsorbed citrine molecules would occur. Gold substrates were chemically modified with 3-mercaptopropionic acid and tert-butyl mercaptan for the preparation of hydrophilic and hydrophobic surfaces, respectively. A pure solution of citrine was dropped and dried on the modified gold substrates and their surface morphology was studied with scanning tunnelling microscopy (STM). The obtained STM images showed multilayers of citrine adsorbed on the modified surfaces. On hydrophobic surfaces, citrine was adsorbed more randomly, formed various non-uniform aggregates, while on hydrophilic surfaces, citrine appeared more aligned and isolated uniform protein clusters were observed. Fluorescence lifetime and anisotropy decay of these dried citrine layers were also measured using the time correlated single photon counting method. Fluorescence anisotropy of citrine on the hydrophobic surface decayed faster than citrine on the hydrophilic surface. From these results we concluded that fluorescence energy migration occurred faster among citrine molecules which were randomly adsorbed on the hydrophobic surface to compare with the hydrophilic surface.

Chitosan-Modified Stable Colloidal Gold Nanostars for the Photothermolysis of Cancer Cells

The preparation and properties of plasmonic gold nanostars (Au NSs) modified with a biopolymer chitosan are reported. The colloidal stability of Au NSs at the physiological pH of 7.5 and their performance in the photothermolysis of cancer cells in vitro were compared with those of gold nanorods (Au NRs). The optical characteristics of chitosan-modified Au NSs dispersed in a medium with pH = 7.5 had higher stability than those of chitosan-capped NRs because of the slower aggregation of NSs. At pH = 7.5, the chitosan-modified Au NRs formed aggregates with highly nonuniform sizes. On the other hand, Au NSs formed small chain-like clusters, in which individual NSs were connected to one another, preferably via association of branches with central cores. It is possible that the difference in areal charge density at these parts of NSs is responsible for their preferred association. Flow cytometry analysis showed the relatively nonequivalent distribution of the chitosan-capped Au NRs across the cell line compared with that of Au NSs because of the fast and nonuniform aggregation of NRs. An in-vitro photothermolysis experiment on J5 cancer cells showed that energy fluences of 23 and 33 mJ/cm2 are necessary to cause complete death of J5 cells incubated with 4 μg/mL chitosan-capped Au NSs and NRs, respectively. When chitosan was used as a surface-capping agent, the Au NSs exhibited higher colloidal stability at the physiological pH than the NRs and lower energy fluence necessary for cell photothermolysis because of more uniform cellular uptake.

NOx Storage and Reduction on Pt/Alumina Catalysts: Effects of Alkaline-Earth and Rare-Earth Metal Additives

A series of Pt/Al2O3 catalysts, modified with alkaline-earth or rare-earth metal oxides, were prepared by the incipient-wetness impregnation method. The catalysts were characterized by N2 sorption, scanning electron microscopy, and transmission electron microscopy. The performance and durability of NOx storage of the catalysts were investigated under a lean-burn/rich-burn cycle process. The effects of reaction temperature on the capacity for NOx and duration of the catalysts were also studied. The transient experiments consisted of a storing phase using a lean gas mixture (NO/O2/N2/C3H6/CO) and a regeneration phase during which the O2 flow was switched off. The catalysts consisted of nonuniform aggregates of very small and distinct particles. The barium-promoted catalyst had better storage capability and duration. On the other hand, the cerium-promoted catalyst had a higher NO storage capability than those without cerium. Comparing the influences of cerium and lanthanum additives, Pt2.5Ce30.5Ba33.4Al100 h...

A model of biocomplexity and its application to the analysis of some terrestrial and marsh eukaryotic microbial communities with an emphasis on amoeboid protists.

Biocomplexity theory has become increasingly important in understanding ecosystem dynamics as we realize that the interactions among subunits in a multi-component system often produce elaborate states that are not easily explained in terms of the individual parts of the system. A Euclidean geometric model of biocomplexity is presented and illustrated using protistan communities. The model is based on three quantitative biotic dimensions (indices) for small subsamples (0.01 g) taken from each sample core of substratum: (1) richness of morphospecies expressed as mean count per 0.01 g, (2) spatial diversity of protists expressed as then umber of unique morphospecies (i.e. those occurring in only one of the 0.01-g subsamples and not in any of the other subsamples), and (3) patchiness (non-uniform aggregation) of the distribution of protists across the 0.01-g subsamples. These three indices are mapped into a three-dimensional Euclidean space model, and the position of each point and its geometric distance from the origin are used as a general index of biocomplexity. The usefulness of the model is illustrated by applying it to a range of terrestrial and marsh communities. Within the set of 15 samples examined in this study, the marsh rhizosphere samples are among the most complex.

Nonuniform region processing on SIMD arrays using the coterie network

Computation on and among data sets mapped to irregular, nonuniform, aggregates of processing elements (PEs) is an important problem in parallel vision processing, arising in segmentation and in support operations for intermediate-level grouping tasks. The difficulty is that the SIMD processors which map so effectively to pixel-based processing are restricted here in data-dependent computations by their limited control mechanisms. Associative processing is an effective means of applying parallel processing to nonuniform computations (Weems 1984), but often results in operating on one data set at a time. We address this problem by introducing an additional level of parallelism we call multiassociativity which provides a framework for performing associative computation on these data sets simultaneously. In this article we present algorithms developed for the coterie network (Weems et al. 1989) to simulate efficiently within nonuniform aggregates of PEs simultaneously the associative algorithms typically supported in hardware at the array level. One result is that algorithms requiring a number of operations proportional to the diameters of the regions in a mesh-connected topology can be executed in constant or logarithmic time using the coterie network. Other results are: the efficient application of existing associative algorithms (e.g., Falkoff 1962; Foster 1976) to arbitrary aggregates of PEs in parallel, and the development of efficient new multiassociative algorithms, among them parallel prefix and convex hull. The multiassociative framework also extends the associative paradigm by allowing operations on and among aggregates of PEs themselves, operations not defined when the entity in question is always an entire array. Two consequences are the support of divide-and-conquer algorithms within aggregates, and communication among aggregates. Numerous multiassociative low-level vision algorithms are presented.